Author: Tim Hunt
MDL-31095 quiz editing: only set quiz->grade to 0 if really necessary.
It is only necessary when there are (non-preview) attempts. However,
after making this change we have to ensure users cannot start attempts
when ->grade > 0 and ->sumgrades = 0.
Display ->grade on the order and paging tab of edit.php, so it is clear
what is going on when you are using that tab.
Finally, improve the error message a student gets if they try to start a
quiz with no questions.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=18dff7575465ee581defdeb2d55f16f904e7635f
http://github.com/moodle/moodle/commit/18dff7575465ee581defdeb2d55f16f904e7635f
+ 2.3 en [cannotstartgradesmismatch,mod_quiz]
+ 2.3 en [cannotstartnoquestions,mod_quiz]